Metasploit is a site which provides information for those engaged in penetration testing and exploit research.
But it fell foul to hackers using the name 'Evil Octal Security Team', which replaced legitimate pages with Asian characters and the English message: "Hacked by Sunwear! Just for fun".
The hack was reported on the blog of security company Sunbelt Software. Comments on the blog made by "HD" - thought to be Metasploit creator H D Moore - said that Metasploit had fallen foul of ARP poisoning.
"Another customer on the same ISP was compromised and used to ARP poison all servers in that subnet," wrote HD. "Metasploit.com servers were not compromised, nor have been to this date. It [the ARP poisoning] was just used to 'deface' metasploit.com for glory."
HD said he rectified the problem by setting a static ARP entry and notifying the ISP. The site now appears to be back to normal.
HD Moore founded the Metasploit project five years ago. He is now director of security research for Breaking Point Systems. Somewhat of a child prodigy, it is thought he has been active on internet mailing lists since the age of 7.